Thursday, June 1, 2006
Flying the AW139
A big ship, AgustaWestland's contender for the U.S. Army's Light Utility Helicopter competition is a strong, agile, pilot-friendly machine that provides an efficient cabin for LUH missions.
There is no denying that every helicopter manufacturer in the universe is trying to wow the flying community with its newest, hottest machines. The ones on this planet are no exception.
AgustaWestland is one of four companies seeking the U.S. Army's Light Utility Helicopter contract, offering a version of its medium-twin AW139 (redesignated from AB139 after the alteration of its partnership with Bell Helicopter). The others are Bell with its 412EP, EADS North America with the Eurocopter EC145 and MD Helicopters with its MD902.
AgustaWestland recently had an AW139 demonstrator and medevac mock-up at Dulles International Airport in the Virginia suburbs of Washington to show off to members of Congress and their staffs, government officials and the press. This gave Rotor & Wing the opportunity to put the helicopter through its paces.
The aircraft operated from the FBO Landmark Aviation (formerly Hawthorne-Piedmont) at Dulles, where I met up with Pietro Venanzi, an AgustaWestland experimental test pilot and the man with whom I would be flying the aircraft.
After a short preflight briefing to discuss the particulars of the ride, this former Italian air force major, who has an extensive background as a fighter pilot and test pilot, took me out to the aircraft we would be flying: N140EV, an AgustaWestland 139 in Evergreen Helicopters' green and white livery. (Evergreen leased AgustaWestland its 2005 model as a flying demonstrator.)
The AW139 is a fairly big helicopter that is slightly longer and wider than the UH-1 Huey. Its wide windows, tilted tail rotor, and gently upswept horizontal stabilizer tips give the ship a unique look. The lines of the hull blend beautifully from nose to tail, but I've flown beautiful aircraft that handled like shopping carts. I wanted to see how the machine would perform.
After a quick walkaround, Pietro slid through the right door and into the pilot-in-command seat. I boarded through the left door with less grace than Pietro, but with the welcomed ease that the wide door gave my horizontally challenged waist line. Two sliding rear doors open to the rear cabin, which (in this aircraft) was setup with four high-back, cloth seats against the back wall and two directly behind the pilot and co-pilot.
The AW139's deck is laid flush with the threshold of the door to make loading palletized cargo easier, especially when using a forklift. Floor tracks are installed to accommodate seats for 15 passengers as well as hard points for tying down cargo. A light gray floor covering made of a non-slip, rubber-like material was also installed in this aircraft.
The flight deck has the usual spaciousness of a corporate-size helicopter, leaving a couple of feet of shoulder space between the flight crewmembers. Head and leg room were ample, making my 5-ft., 10-in. frame comfortable with the seat and pedal positions set as they were. A five-point harness system added to the feeling of security and oneness with the machine. My left hand dropped to discover the collective grip and thumb controls right where I like them; the cyclic was situated in a natural position for my right hand. The pedals were comfortably spaced and the center console did not rub against my leg (the latter of which I find annoying in some helicopters).
With ground power connected, Pietro flipped a switch and awakened the electrical system. Instantly, four Honeywell Primus Epic multi-function displays (MFDs), two for each pilot, came alive with a colorful array of information. My pair presented standard flight and navigation readouts on the left display and engine system status on the right one. All parameters were easy to read and understand and, much to my delight, were not recessed as deeply under a glare shield as the instruments in most other aircraft of similar size. Even so, the bright sunshine did not have a detrimental effect on my ability to read them.
As with most MFDs, the information displayed could be rearranged, minimized and augmented to suit personal preferences with great simplicity. Pietro used his to flash through a series of pre-start checks on everything from hydraulics to fuel. He also had views from the two outside video cameras appear above the engine information already displaying on my right MFD. (External cameras can be placed almost anywhere, but on our aircraft one showed the cargo hook, and the other looked straight down where the load would have hung.)
Most of the switches and buttons on the flight deck are standard fare aboard any well-dressed twin turbine helicopter. These included audio controls, start switches, and accessory selectors. All are well placed, regardless of which pilot seat you occupy and can be positively manipulated with gloved hands.
With my pre-start orientation complete, Pietro signaled the ground crew that he was ready to start the aircraft. After receiving a thumbs-up in return, the 43-year-old native Italian ran through his start-up checklist.
Pietro advised me that the AW139 is equipped with full-authority digital engine controls (FADEC), and directed me to rotate the start switch for engine No. 1 to the "Idle" position. With the turn of a dial on the center console, the FADEC slowly brought the first sleeping Pratt & Whitney PT6C-67C turbine engine to life, as evidenced by the gentle rumble in the airframe and the activity on the bar graphs of our displays. When the left engine settled into its comfort zone, I brought its twin on line.
After a quick scan of the aircraft's status, Pietro signaled the ground crew to disconnect the external power unit. Once they cleared, I rotated each start switch to the "Flight" position and watched the five-bladed rotor system spin up even higher. Within seconds, the bar scales on the engines were well into the green range, signaling that 1,531 maximum continuous shp (1,679 shp takeoff) was available.
N140EV was equipped with a two-head control (one for each pilot) Honeywell TR866 radio/transponder, a part of the Primus Epic system. Voice and navigation frequencies and transponder codes appear on a single digital display panel above a keypad. After receiving our clearance information, Pietro entered our assigned transponder code and tower frequency and advised the controller that we were ready to depart.
Once cleared for takeoff, he exchanged a thumbs-up with the ground crew and pulled up on the collective. N140EV got light on its tricycle landing gear and lifted nose-first into a hover. After a 45-deg. pedal turn to the right and an aggressive climb-out, Pietro retracted the landing gear, and turned north across the Virginia country side.
Immediately, I noticed the relatively unobstructed view ahead and to each side. The instrument panel and glare shield do not cramp the view out front. In fact, I was able to see around the side for a partial look down. Hull pillars and door frames did not severely restrict scanning for traffic on either side of the aircraft.
Removing my headset for a moment revealed a comfortable noise level. An intercom was still needed, but engine and transmission noise were not deafening.
As we turned on course for the short ride to Leesburg Executive Airport (JYO), Pietro came over the intercom with the four words every passenger with a pilot's license wants to hear: "You have the controls." Easing my feet onto the pedals and my hands onto the cyclic and collective, I replied, "I have the controls."
Having just flown a brand new AgustaWestland A119 a couple of weeks before, I was already familiar with the company's force trim system. Depressing a button where your thumb naturally falls on the cyclic, and squeezing a trigger where your index finger usually grabs the collective activates a system that constantly trims the controls to the spot you move them to. Releasing the button and trigger stops the trim motors, holding the cyclic and collective where they are.
In the AW139, the forced trim is something just this side of an autopilot. After pulling in 62-percent torque, and pitching for 130 kt., I got straight-and-level, hands-off flight that held heading and attitude with remarkable accuracy. If things aren't exactly right in the pitch or roll axes, they can be tweaked using a hat switch on the cyclic. In fact, I was able to park the aircraft in a 600-ft.-agl hover, then put my hands in my lap and both feet on the floor and watch the aircraft hold its station.
Surprisingly enough, depressing the force trim switches comes naturally after a few minutes. For pilots who want to do it the old-fashioned way, the system can be deactivated using a console-mounted switch.
While all pilots have their own preference for how much effort they want to expend moving the cyclic, the AW139 falls right where I like it: somewhere between the light feel of a Robinson R22 and the stiff feel of an MD500. It isn't vague, but it doesn't fight back, either. Minor adjustments to any flight control in the AW139 gave me just enough feedback to verify that the aircraft and I were always on the same page. Dramatic maneuvers, such as snap rolls and quick stops, were crisp and fed valuable information back through the stick.
Once we arrived in the pattern at Leesburg Regional, a suburban airport about 28 nm northwest of Washington, I shot a normal approach to Runway 35. The AW139 maintained its poise all the way down with little regard for the 25-kt. quartering headwind and accompanying gusts to 30 kt. Toward the bottom, translational lift dropped out with little more than a mild shiver.
In a hover, the AW139 hung with the usual nose-up attitude inherent in other aircraft of that size. Squeezing in some pedal spun the helicopter effortlessly around its vertical axis; first in one direction, then the other. After getting realigned with the runway, I eased the ship into a normal takeoff, which was... well... normal.
While turning crosswind, Pietro suggested that I take my feet off the pedals and fly the pattern back to a normal approach. At 100 kt. with a right quartering tailwind, the AW139 remained in trim throughout the downwind leg using its own trim system. The "ball," which is actually depicted as a triangle on the Honeywell digital horizontal situation indicator (HSI), pretty much stayed locked in the center position through base, final, and termination over the numbers, with no pedal inputs needed.
The next trip around the pattern gave Pietro time to set me up for one-engine-inoperable training, which consisted of a quick briefing and flipping a console switch marked "OEI TNG" to No. 1 or 2, depending upon which engine he was going to "fail."
The OEI TNG switch does not fail the selected engine. It merely lowers the power across both engines to a level that only one engine would deliver, while making the instruments read as if one engine is dead and the other is still working. When Pietro simulated the failure of No. 2, its power level meter dropped to zero, but No. 1 still read as if it were operating normally.
With one engine pretending to be out, my left MFD displayed a small, lone bar graph under my HSI. Pietro explained that when one engine is out, that single graph will display whichever system parameter is about to reach its operational limit. So, if I'm about to over-torque the rotor, the display will be the torque gage. If I'm about to over-temp the engine, that display will show turbine outlet temperature. Consequently, I only needed to scan one bar graph, instead of several, to see the condition of the most critical parameter.
Another aspect of the OEI TNG mode is an automatic training-cancellation feature. Pietro demonstrated the cancellation mode by trying to over-torque the rotor system. As the bar climbed, the synthesized voice said something to the effect of, "Warning, Torque!" As the torque approached the red zone, the OEI TNG switch turned itself off, and brought both engines back to full power. The engine-out training session was automatically cancelled by the aircraft before anything actually exceeded a limitation.
For the next takeoff, Pietro took the controls. He instructed me to fail an engine as soon as he got about 30 ft. into a pure vertical climb. As ordered, I moved the switch to simulate a flame-out in engine No. 1. As the power dropped out, Pietro lowered the collective and pitched the nose down slightly. But instead of coasting the aircraft back onto the runway, he pushed the ship through translational lift, jacked in some more power, and eased 12,350 lb. of helicopter and load back into the pattern. "See?" he said proudly. "I can fly away on one engine if I want it to." (I was alright with that!)
Since one engine was already a victim of "death by simulation," I figured it was a good time to try an autorotation. Pietro played along, and sat back for the ride.
After making the obligatory announcement over the unicom frequency and running through a short checklist, I entered a straight-in OEI autorotation. The ride down was uneventful, even as I played with the rotor rpm. It offered an excellent glide ratio, in spite of the 20-kt. quartering headwind, and provided great visibility through its huge windscreen. Being unfamiliar with where the tail would end up, I flared a little higher and a bit more cautiously than I would have in a real emergency, and just to be on the safe side, I terminated the maneuver in a hover. Besides, I had seen what I needed to see: The AW139 would not surprise a pilot in an autorotation, and could probably be very forgiving.
Back on the ground, Pietro gave me a demonstration of the AW139's agility. With landing gear extended, he lifted the aircraft 5 ft. off the runway centerline, turned the nose 90 deg., and flew sideways at about 25 kt.; first right, then left. He terminated with another pedal turn and a quick stop with a near quartering tailwind. I repeated the maneuvers with almost the same ease, noting how effortless it was to finesse the aircraft into doing anything I wanted it to.
I flew the final takeoff. As Pietro thumbed through his publications looking for a suitable instrument approach back to Dulles, I took another general assessment of the aircraft's ride. After more than an hour in the saddle, I was still feeling good. There were no "hot spots" in the seats, and the location of the collective, cyclic and pedals remained comfortable. The outside air temperature was 7C, so there was no need for heat or air conditioning. A set of well-placed circular air vents on my side of the instrument panel provided plenty of comfort for the trip back to Dulles.
After receiving clearances and vectors to intercept the ILS for Runway 1R at Dulles, Pietro dialed in the appropriate navaids and switched on the three-axis autopilot. He explained that a four-axis system capable of true auto-hovering should be certified by the year's end. A visual map, traffic collision avoidance system, and ground proximity warning system are due to be certified by mid-year.
With our feet on the floor and our hands off the controls, N140EV rolled into a final approach, and rode the slope to the runway, keeping the needles dead-centered all the way down. At 40 ft. agl, Pietro released the autopilot, and manually air taxied the helicopter back to the general aviation parking area.
After disembarking, we walked over to the LUH mock-up. AgustaWestland used it to demonstrate the aircraft's medevac configuration for the Army's evaluators. My tour guides here were project officer Pat Thompson and mock-up administrator Robert Platt. They work for Colorado-based Tactical Solutions Group, which designed the AW139's medevac cabin.
The passenger cabin was equipped with the usual array of medical gear, all mounted in or on the aft wall. Below it was a passage to the tail-section baggage compartment, which held a Stokes rescue basket and gear Pat could easily pull into the cabin.
In the center of the aft cabin floor was a track-mounted pedestal with two stacked patient tables. Once a patient is on one table, a scissor-like mechanism raises it so that another can be placed on the one below. When loaded, the pedestal can be swiveled and moved around the cabin as needed, with enough room to secure two stretchers or Stokes baskets to the floor. Four mesh seats for crewmembers were mounted near the sliding side doors--two facing forward and two aft.
At the end of the day, I scored the AgustaWestland AW139 high on my list of medium twins. It's a big ship, and my guess a bit more expensive for the Army to buy than its smaller competitors, the EADS EC145 and MD Helicopters MD902. But the AW139 is certainly comfortable, strong and agile. It provides a efficient cabin for LUH missions and is a pilot-friendly machine that will do as much or as little as you ask it to. Heck, it did everything except fill out my logbook!